Pressurised metered dose inhaler (pMDI) devices are the most popular and widely prescribed devices for respiratory drug delivery for treatment of asthma and other respiratory conditions.
In such devices, the active ingredient/drug is typically provided in the form of a solution or suspension held in a pressurised canister. Actuation of the canister is typically achieved by depressing the canister towards the body of the device. This causes an interaction between the canister and a valve seat that causes a metered dose to be ejected from the canister, along with a propellant gas (typically a hydrofluoroalkane (HFA) gas). The dose becomes aerosolized and available for inhalation by the patient.
Dry powder inhaler (DPI) devices are an alternative to these aerosol-based inhalers, and well known in the art, in which a powdered respiratory drug may be held, for example, within a capsule which is perforated by the device as the patient inhales. An insufficient inhalation rate will result in reduced dose delivery and incomplete de-aggregation of the powdered drug potentially leading to poor control of the respiratory problem.
The perception is that these devices are easy to use but this is far from the reality: seemingly simple steps such as coordination of actuation of the device with inhalation, and inhaling at the appropriate flow rate are often performed incorrectly.
It is known to provide a spacer or a holding chamber to assist patients, especially young and elderly patients, with their inhaler use. These adapters are known to improve the direction and deposition of medication delivered by drug delivery inhaler devices.
Spacers are relatively simple adapters (often in the form of a simple tube or chamber) which extend the mouthpiece of the drug delivery inhaler devices thus slowing and directing the medication into the patient's lungs rather than impacting and sticking to the back of their mouth.
Holding chambers are provided with a valve, typically a one-way valve allowing inhalation from but not exhalation into the chamber, and the medication is trapped within the holding chamber allowing the medication to be inhaled slowly. The use of these valved holding chambers eliminates the requirement that slow deep inhalation coincides with the actuation of the pMDI drug delivery inhaler device.
It is known to use non-conventional devices as spacers for use with drug delivery inhaler devices. For example, Sheth et al. (Annals of Allergy, Asthma and Immunology, 113 (2014) 55-62) discuss the successful use of various house-hold items such as a toilet paper roll, a paper towel paper roll, rolled paper and a plastic bottle as spacers for use with a pMDI. Paper cups have also been proposed as an effective spacer (Wllemse, et al. Respiratory Medicine, 97 (2003), 86-89). In this study, the mouthpiece of the pMDI was inserted into a cross-cut formed in the base of the paper cup and the pMDI actuated whilst the opening of the cup was blocked with a user's hand. The user then removed their hand and inhaled from the cup opening.
These non-conventional spacers have the advantage that they are low cost and easily available without a prescription and yet they have proved to be clinically effective.
Whilst such spacers may be ideal for developing countries, they are not, however, suitable for some settings in which there is a requirement for low-cost, disposable spacers. For example, a recent UK Government initiative requires UK schools to provide drug delivery inhaler devices and spacers for emergency use within the school (http://www.asthma.org.uk/get-involved-inhalers-in-schools).
Known, conventional plastic spacers require thorough cleaning after use, especially if they are to be used by more than one patient and hence this cleaning places a burden on the school staff and a contamination risk if cleaning is not carried out effectively. The non-conventional devices discussed above, whilst cheap and disposable, are unlikely to meet the requirements for spacer provision set by the UK Government.
Inserting a pMDI mouthpiece into a cross-cut in the base of a paper cup as described above, will not form a good seal and so there may be leakage and wastage of the drug. Furthermore, this arrangement is incapable of directing the angle of entry of the drug plume into the cup body. Finally, any lose paper pieces or dust will interfere with the drug flow and could be inhaled by the user.
WO01/05458 describes a disposable, cardboard holding chamber which contains two one-way valves. The mouthpiece is provided by two holes in the cardboard. Such a mouthpiece will be unfamiliar to a child and they may also find it difficult to form a seal around these holes.
Accordingly, there is a need for a low cost, disposable spacer that can easily be used by children (as well as other patients).